1. Field of the Invention
This invention relates to a process of co-nitrating a mixture of trimethylolethane and diethylene glycol. More particularly this invention relates to a process of co-nitrating a mixture of trimethylolethane and diethylene glycol with an excess of from about 60 to about 100% by weight of nitric acid above the stoichiometric requirement.
2. Description of the Prior Art
Commercial explosives and gun propellants, based on nitroglycerine have been known and widely used for years. The nitroglycerine, alone or mixed with sensitizers such as nitroglycol, imparts desirable properties to explosive and propellant compositions. However, due to the very high sensitivity of nitroglycerine there are certain disadvantages in its use. Also nitroglycerine is a powerful vasodilator causing headaches among workers exposed to its vapor.
More recently explosive sensitizer compositions have been used which have lower impact sensitivity and often low vapor pressure. For example, U.S. Pat. No. 3,238,074 discloses explosive compositions containing up to 40% of a "known sensitizing explosive" used alone or in admixture. Among the sensitizing explosives recited in the patent are diethylene glycol dinitrate and trimethylolethane trinitrate. The mixture of diethylene glycol dinitrate and trimethylolethane trinitrate is also mentioned in a number of patents as energetic plasticizers in propellants. See, for example, U.S. Pat. Nos. 3,306,790; 3,639,183; 3,844,856; and 3,951,706.
The nitrate sensitizers are generally prepared by nitrating the polyols with nitric acid. For example, U.S. Pat. No. 3,423,256 discloses co-nitrating a mixture of a polyol, such as ethylene glycol, and trimethylolethane with a mixture of sulfuric and nitric acids. The patentee states that the amount of nitric acid employed is normally that stoichiometrically required to nitrate the free hydroxyl groups of the polyol. The patentee goes on to indicate that a small excess, ranging from about 5 to 25% can be used to ensure completion of the nitration.
Diethylene glycol and trimethylolethane can be co-nitrated in the usual way, as reported in the prior art, using the amount of nitric acid stoichiometrically required to nitrate the free hydroxyl groups or a small excess. However, if the normal nitration process if followed, one obtains a spent acid which is unstable and will decompose exothermically in a few hours.